15 Tiny Details You Missed the First (and Second) Time You Read Harry Potter

More than 20 years later, J.K. Rowling's iconic book series still holds plenty of surprises for fans. Caution: spoilers ahead!

The Mirror of Erised offered clues about its purpose

It was a magnificent mirror, as high as the ceiling, with an ornate gold frame, standing on two clawed feet. There was an inscription carved around the top: Erised stra ehru oyt ube cafru oyt on wohsi.

Harry Potter and the Sorcerer’s Stone

Professor Dumbledore explains to Harry in the first book of the series that the Mirror of Erised (“desire” spelled backward) reveals “nothing more or less than the deepest, most desperate desire of our hearts.” But if Harry had read the inscription in a mirror, he could have decoded the backward message, “I show not your face but your heart’s desire.”

Fred and George Weasley were born on April Fool’s Day

“They can’t do that!” said George Weasley, who had not joined the crowd moving toward the door, but was standing up and glaring at Dumbledore. “We’re seventeen in April, why can’t we have a shot?”

—Harry Potter and the Goblet of Fire

It’s no trick; everyone’s favorite pranksters were born on April 1, 1978, according to Pottermore.com. If you love to laugh as much as the Weasley twins, check out 23 Harry Potter jokes every muggle should know.

Snape hints about his love for Lily Potter from the start

“Potter!” said Snape suddenly. “What would I get if I added powdered root of asphodel to an infusion of wormwood?”

—Harry Potter and the Sorcerer’s Stone

It sounds like nonsense meant to trip Harry up in his first potions lesson. But Rowling is using the Victorian language of the flowers to express Snape’s regret over Lily’s death. “Asphodel is a type of lily and means ‘remembered beyond the tomb’ or ‘my regrets follow you to the grave’ while wormwood is often associated with regret or bitterness,” explains Pottermore.com. Take a deeper dive into Snape’s first words to Harry.

Things get dark in chapter 13

Unlucky 13 strikes again. In that chapter of each book, an evil character or Horcrux is introduced or becomes crucial to the plot. Think: Tom Riddles’ diary appearing in Harry Potter and the Chamber of Secrets, Mad-Eye Moody performing magic on students in Harry Potter and the Goblet of Fire, and Harry’s first detention with Umbridge in Harry Potter and the Order of the Phoenix.

Unicorn blood foreshadows Horcruxes

“The blood of a unicorn will keep you alive, even if you are an inch from death, but at a terrible price. You have slain something pure and defenseless to save yourself, and you will have but a half-life, a cursed life, from the moment the blood touches your lips.”

—Harry Potter and the Sorcerer’s Stone

Firenze the centaur is explaining the consequences of killing a unicorn to Harrybut it kind of sounds like creating a Horcrux too, doesn’t it? Rowling began laying down the groundwork for the final book in the series long before Harry Potter and the Half-Blood Prince was published

Fred and George accidentally attacked Voldemort

One morning in mid-December, Hogwarts woke to find itself covered in several feet of snow. The lake froze solid and the Weasley twins were punished for bewitching several snowballs so that they followed Quirrell around, bouncing off the back of his turban.

—Harry Potter and the Sorcerer’s Stone

At this point in the story, Voldemort is sharing Quirrell’s body and his face is hidden underneath his turban. That means technically Quirrell was a temporary Horcrux, and also, the Weasley twins were hitting Voldemort in the face with snowballs.

Rowling hinted about Snape’s Legilimency skills

Could Snape possibly know they’d found out about the Sorcerer’s Stone? Harry didn’t see how he could—yet he sometimes had the horrible feeling that Snape could read minds.

—Harry Potter and the Sorcerer’s Stone

We find out in Order of the Phoenix that Snape has mastered Legilimency, which means he can “delve into the minds” of others. So it’s possible he was onto our heroes, after all, even way back when.

Ron’s joke about Tom Riddle is spot-on

“Maybe he got thirty O.W.L.s or saved a teacher from the giant squid. Maybe he murdered Myrtle; that would’ve done everyone a favor.”

—Harry Potter and the Chamber of Secrets

As Harry, Ron, and Hermione wonder what Riddle did to receive a Special Award for Services to the School, Ron throws out this goofy speculation. But Riddle actually did kill Moaning Myrtle when he released the basilisk. Good guess!

Professor Trelawney deserves more credit

“I dare not, Headmaster! If I join the table, we shall be thirteen! Nothing could more unlucky! Never forget that when thirteen dine together, the first to rise will be the first to die!”

—Harry Potter and the Prisoner of Azkaban

More evidence of Professor Trelawney being ridiculous—or so we’re led to believe. But it turns out there were already 13 diners, thanks to Pettigrew (as Scabbers). Dumbledore rose first—and is the next to die. This also holds true later; Sirius rises first at Grimmauld Place, and Lupin does at a gathering to mourn Mad-Eye Moody.

The Black family has a celestial theme

Many Black family members are named after stars or constellations. The most significant is Sirius, often called the “Dog Star” and is a prominent part of the constellation Canis Major (“Greater Dog”). But there’s also Bellatrix (“Female Warrior,” in the Orion constellation), Regulus (“Little King”), Andromeda (“The Chained Maiden”), and Alphard (“Solitary One” in the snake-like constellation Hydra). Astronomers recently created their own Harry Potter constellation, too.

The Marauder’s Map contains a plot clue

“Messrs. Moony, Wormtail, Padfoot, and Prongs, Purveyors of Aids to Magical Mischief-Makers, are proud to present the Marauder’s Map.”

—Harry Potter and the Prisoner of Azkaban

The Marauders died in the reverse order of the way they are listed on the map: James (Prongs), Sirius (Padfoot), Pettigrew (Wormtail), and Lupin (Moony). Obsessed with the Marauders? Sneak a peek at the house that served as Harry’s home in Godric’s Hollow.

Harry and Ron’s prophecies come true

“Okay …On Monday, I will be in danger of — er — burns.”

“Yeah, you will be,” said Ron darkly, “we’re seeing the skrewts again on Monday. Okay, Tuesday, I’ll…erm…”

“Lose a treasured possession,” said Harry, who was flicking through Unfogging the Future for ideas.

“Good one,” said Ron, copying it down. “Because of …erm…Mercury. Why don’t you get stabbed in the back by someone you thought was a friend?”

—Harry Potter and the Goblet of Fire

Unfortunately for Harry, these things actually do come to pass. He’s risking burns when he faces a dragon in the first task, he nearly loses Ron in the second task, and later, Ron stabs him in the back by jealously refusing to speak to him.

Hermione’s Patronus revealed her future

Hermione’s Patronus, a shining silver otter, was gambolling around her. “They are sort of nice, aren’t they?” she said, looking at it fondly.

—Harry Potter and the Order of the Phoenix

Otters are Rowling’s favorite animal, and she has said before that she was a bit like Hermione when she was growing up. But otters also happen to be part of the weasel family—a sly nod to the Weasley clan, which Hermione will eventually marry into.

Voldemort was a senior citizen

Harry, with the unerring skill of the Seeker, caught the wand in his free hand as Voldemort fell backward, arms splayed, the slit pupils of the scarlet eyes rolling upward.

—Harry Potter and the Deathly Hallows

He Who Must Not Be Named was born on December 31, 1926, making him 71 years old when he died in the Battle of Hogwarts on May 2, 1998.

The last dedication had a special format

You probably raced right by the dedication page in Harry Potter and the Deathly Hallows in order to finally find out what happened to Harry and his friends. But if you did take a minute to check it out, you’d see that Rowling’s final dedication is printed in the shape of a lightning bolt, just like the scar on her hero’s forehead.

If you’re a diehard Harry Potter fan, try out this Harry Potter trivia.

Chrisanne Grisé
Chrisanne Grisé covers culture for Reader’s Digest. Her work has also appeared in The New York Times Upfront, Martha Stewart Weddings, Food Network, Fitness, and Parents, among other publications. She earned a BS in journalism from Emerson College. Follow her on Twitter or Instagram.